Though phthalates offer many benefits in the manufacturing process, dibenzoate plasticizers have a proven track record of safety and reliability.
Phthalates can be found in nearly every product on the
market. It is estimated that more than a billion pounds of phthalates are
produced worldwide each year for use as plasticizers, fragrance carriers in
perfumes and additives in hairspray, lubricants, and wood finishes.
Over the last decade, however, phthalates have come under increased scrutiny
for their potentially adverse health effects. Early tests linked high doses of
phthalate exposure to cancer and infertility. More recently, low levels of
phthalates have been associated with fetal development problems - specifically
in male reproduction. In fact, some scientists claim phthalates have an
anti-androgenic effect. This low-level risk, combined with the pervasiveness of
phthalates in our environment, has caused regulating agencies worldwide to
seriously examine the continued use of phthalates.
The Registration, Evaluation and Authorization of Chemicals (REACH) initiative
is a recent regulatory effort to propose restrictions on phthalate use. Though
it originated in Europe, the effects of REACH
are being felt around the globe. In addition, other organizations and
legislative bodies, including many in the U.S., continue to question the
potential risk and liability of phthalates.
Investigations into the safety of certain phthalates date back to long before
REACH was conceived. One of the most commonly used plasticizers in many
consumer products, including toys, is di-2-ethylhexyl phthalate, or DEHP. Toys
containing DEHP were voluntarily recalled by many toy manufacturers selling
them in the U.S.
because the International Agency for Research on Cancer declared DEHP a
probable human carcinogen in 1982.
The Center for the Evaluation of Risks to Human Reproduction (CERHR) convened a
panel to review any potential health risks to human reproduction caused by
phthalates in 1999. The CERHR issued a draft report in 2000 that discussed
findings of low to negligible concern on most of the phthalates reviewed.
However, the panel expressed varying levels of concern for infants, children
and pregnant women exposed to DEHP. The phthalate has since been linked to
problems with sperm formation, low sperm counts and male genitalia deformities
in trials with rodents. The term “phthalate syndrome” was coined in 2005 for
use in the medical community to describe documented changes in the male
In response to consumer concerns, the Consumer Products Safety Commission
called for a voluntary phaseout of DEHP in toys and medical devices. California issued a
state ban on all children’s toys containing phthalates in April 2008. House
Bill 5601 banned children’s products containing lead, phthalates or
bisphenol-A. Shortly thereafter, the U.S. Congress passed the Consumer Product
Safety Improvement Act (CPSIA), which placed tight restrictions on allowable
lead and phthalate levels in children’s toys and childcare articles.
The future for phthalates continues to be questioned as more studies are
published correlating phthalates with negative effects on human health and the
environment. As a class, phthalates have often been described as moderately
persistent with the potential to bioaccumulate in fat tissue. Some may be
broken down in the body, although degradation and excretion rates differ
between adults and children. In addition, phthalates have been shown to
strongly absorb into the soil and biodegrade slowly.
Along with stricter regulations resulting from REACH, manufacturers are
required to place EU warning labels to warn of reproductive hazards and
potential toxicity to humans and the environment. This will only serve to
increase consumers’ health concerns and focus more attention on the
environmental impact of phthalates.
The REACH initiative requires potentially harmful chemicals to be classified by
their degree of perceived risk. Based on the studies and negative publicity,
many phthalates - including DEHP and butyl benzyl phthalate (BBP) - have been
prioritized as substances of very high concern (SVHC). This means that
manufacturers that previously relied on phthalates must decide whether to
accept the added liability and limitations of using an additive that has
already been classified as potentially dangerous or identify a viable, safer
Table 1. Plasticizer Compatibility
Dibenzoate Plasticizers Provide an Alternative to Phthalates
Although phthalates offer many benefits in the manufacturing
process, a number of alternatives offer equal performance, as well as
substantial safety, legislative and environmental advantages. Dibenzoate
plasticizers are an attractive option. Unlike some newer alternatives, such as
diisononyl cyclohexane-1,2-dicarboxylate (DINCH), dibenzoate plasticizers have
a proven track record of performing safely and reliably. They have been in use
for a variety of applications worldwide for more than 40 years. Dibenzoate plasticizers
are highly solvating monomeric plasticizers that decrease processing times and
lower processing temperatures. In addition, they offer superior resistance to
extraction by solvents such as kerosene, cotton seed oil and soapy water. From
a health and environmental perspective, the European Chemical Agency (ECHA)
listed dibenzoate plasticizers as a preferred alternative to phthalates in May
Certain grades of dibenzoate plasticizers are more environmentally friendly
than others. Many require no warning labels and are even approved by the FDA
for use in food packaging.
Other benefits include the following.
Compatibility with a variety of polymers and
Dibenzoate plasticizers are compatible
with many polymeric materials, including ethylene vinyl acetate (EVA),
polyvinyl chloride (PVC), styrene-butadiene rubber (SBR), ethyl cellulose (EC),
nitro cellulose (CN), cellulose acetate butyrate (CAB), polyurethane (PU) and
acrylics (PMMA). Although no one material is universally solvent or compatible
in every resin type, dibenzoates offer a good balance of compatibility, as
shown in Table 1.
A proven track record in waterborne
adhesives, caulks and sealants.
Figure 1. U.S. Consumption of Dibenzoate Plasticizers
plasticizers have been successfully used in adhesives, caulks and sealants for
more than 25 years. Waterborne adhesives represent over 50% of the sales of
these plasticizer types, followed by caulks and sealants, which also represent
significant end uses (see Figure 1). Commercial sales of dibenzoate
plasticizers date back to the early 1980s, according to data from the Chemical
published by SRI International.
Low in toxicity, non-mutagenic and non-carcinogenic.
The U.S. EPA High Production Volume Information System (HPVIS 2009) lists both
diethylene glycol dibenzoate (DEGDB) and dipropylene glycol dibenzoate (DPGDB)
as non-mutanogenic and non-carcinogenic. Furthermore, the ECHA 2009 assessment
lists DPGDB as not persistent, not bioaccumulative and not toxic, making it a
materials are not readily biodegradable, dibenzoate esters will hydrolyze in
water and biodegrade under certain conditions. The US HPVIS 2009 indicates
DPGDB is ultimately biodegradable under anaerobic conditions when tested in
accordance to USEPA Method 796.3140. DPGDB is also readily biodegradable under
the aerobic conditions of the OECD guideline method 301B. The Danish QSAR
calculated the half-life of DPGDB to be 78 days.
21CFR food-contact approval.
Many materials are not cleared by the U.S. Food and Drug Administration (FDA)
for food contact applications; however, dibenzoates have clearance for certain
applications, subject to restrictions. In fact, the choices of plasticizers
become increasingly narrow, particularly as the anticipated food contact or
potential for extraction increases. Very few plasticizers are approved for
direct contact applications. Both DEGDB (CAS 120-55-8) and DPGDB (CAS
27138-31-4), and mixtures thereof, are among the chemicals the FDA allows to be
used in the following specific applications:
- 21CFR § 175.105(c)
- 21 CFR § 176.170
- 21 CFR §176.180
Because FDA regulations may be complex and are subject to change, manufacturers
must carefully review all application requirements, both anticipated and
unanticipated uses for the product, and current list of cleared materials.
Highly soluble in PVC with a
solubility coefficient similar to PVC for easy fusing.
Table 2. Solubility Parameters
Dibenzoates display similar characteristics to BBP (see Table 2), making these
materials especially good replacement choices.
Lower production costs based on ability to operate
lines at lower temperatures.
The energy required to
perform heat seal and drying operations of packaging and other coated materials
is directly related to the Tg
and MFFT. Lower energy
consumption can lead to cost savings and reduced greenhouse gas emissions.
Effective plasticization, which can be achieved with dibenzoate plasticizers,
will lower the MFFT, Tg
and energy consumption, as well
as deliver the desired physical properties.
Table 3. Volatile Organic Chemical Content of Select Plasticizers
VOC levels show dibenzoates to be comparable to many of the common C7
ester phthalates, but substantially lower than other alternatives (see Table
3). While there is a relationship between molecular weight and VOCs, there are
other factors that come into play, such as the presence of low-molecular-weight
As a result of these benefits, adhesives plasticized with dibenzoate esters are
ideal for the following applications: carton sealing/forming in the packaging
industry; book binding and labeling; fibers and non-woven fabrics in textiles;
and forming decorative wall panels, window frames, mastics and caulking
compounds in construction. To a lesser degree, these high-performance
plasticizers are also used to produce furniture, luggage, shoes and flooring.
End users who have traditionally relied heavily upon phthalates have looked
carefully at alternatives in recent years. The flooring industry is one such
example. The Toxic Use Reduction Institute at the University of
Massachusetts-Lowell (TURI) indicated that DPGBD was an effective substitute
for DEHP in resilient flooring. This conclusion was made after consideration of
the performance and function needs of the manufacturer and customer, as well as
the health, safety, environmental, and financial assessment of alternative
plasticizers and functional replacements. Similar testing conducted in Europe to evaluate alternatives to the BBP plasticizer
primarily used in flooring applications also concluded that DPGDB provides a
good technical replacement.
Evaluations have also been conducted in other applications, such as medical
devices, neonatal care products, toys and wall covering. In each case, careful
consideration was given to the end performance needs of the final article, the
other components used in the product, processing and end-use conditions,
regulatory requirements, and cost considerations. While no single product meets
every need, the final selection is based upon achieving the optimal balance in
The Future of Manufacturing and Regulations
Regulations are expected to increase worldwide. REACH has
set a precedent in Europe, but given the
global nature of our economy, nearly all manufacturers are affected. Other
countries and governing agencies are already generating similar initiatives.
Whether future studies confirm or negate current theories regarding the adverse
health and environmental impact of phthalates, in our precautionary culture the
questions that have been raised to date will likely be sufficient to cause
additional legislative restriction and avoidance by “informed” consumers.
Today, largely as a result of instant access to online reports, press articles
and community blogs, consumers are better educated and more active in demanding
Manufacturers need to be prepared to respond with responsible chemical
selections. In the phthalate replacement arena, dibenzoate plasticizers offer a
safe, reliable, cost-effective alternative.
For more information, contact the authors by
e-mail at Shamsi.Gravel@emeraldmaterials.com or Emily.Mcbride@emeraldmaterials.com.